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arXiv 0903.0838astro-ph.HE
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船帆座X-1高度结构化的风

Highly structured wind in Vela X-1

I. Kreykenbohm, J. Wilms, P. Kretschmar, J. M. Torrejon, K. Pottschmidt, M. Hanke, A. Santangelo, C. Ferrigno, R. Staubert

摘要:

我们提出了一个深入的分析的光谱和时间的行为,一个长期的几乎不间断的积分观测船帆座X-1在2003年11月/12月。除了已经很高的活动水平外,船帆座X-1还出现了几个非常强烈的耀斑,最大强度超过5克拉布在20-40千电子伏波段。此外,船帆座X-1显示出几个关闭状态,其中源变得无法用ISGRI检测到。我们将耀斑和关闭状态解释为由于光学伴星的强结构风:当船帆座X-1遇到密度大大降低的风中的空腔时,通量下降,从而可能触发螺旋桨效应的发生,从而抑制进一步的吸积,从而产生关闭状态。船帆座X-1中触发螺旋桨效应所需的密度下降与OB星风密度的理论论文预测的数量级相同。当船帆座X-1在风中遇到一个密集的斑点时,同样的结构风可以引起巨大的耀斑。进一步的时间分析表明,一个短暂的QPO的周期约为6800秒。光变曲线中存在QPO的部分非常接近于关闭状态,并且刚好在高强度状态之后,因此表明所有这些现象都是相关的。

英文摘要:

We present an in-depth analysis of the spectral and temporal behavior of a long almost uninterrupted INTEGRAL observation of Vela X-1 in Nov/Dec 2003. In addition to an already high activity level, Vela X-1 exhibited several very intense flares with a maximum intensity of more than 5 Crab in the 20-40 keV band. Furthermore Vela X-1 exhibited several off states where the source became undetectable with ISGRI. We interpret flares and off states as being due to the strongly structured wind of the optical companion: when Vela X-1 encounters a cavity in the wind with strongly reduced density, the flux drops, thus potentially triggering the onset of the propeller effect which inhibits further accretion, thus giving rise to the off states. The required drop in density to trigger the propeller effect in Vela X-1 is of the same order as predicted by theoretical papers for the densities in the OB star winds. The same structured wind can give rise to the giant flares when Vela X-1 encounters a dense blob in the wind. Further temporal analysis reveals that a short lived QPO with a period of ~6800 sec is present. The part of the light curve during which the QPO is present is very close to the off states and just following a high intensity state, thus showing that all these phenomena are related.

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